A cylindrical battery made by connecting together in series a plurality of the accumulator cells which store electricity in batteries and condensers and the like is proposed for example in JP-A-11-26321. This cylindrical battery having a series accumulator cell connection structure of related art is shown in FIG. 23.
Referring to FIG. 23, a plurality of accumulator cells 301 configuring a cylindrical battery 300 are connected in series. The series-connected accumulator cells 301 are received in a cylindrical metal case 302.
Each of the accumulator cells 301 is a wound body made by forming polarizing electrodes on the faces of collector foils to form a positive electrode body and a negative electrode body and winding the positive electrode body and the negative electrode body separated by a separator into a roll.
The accumulator cells 301 each have a positive lead part 303 consisting of a part of the collector foil of the positive electrode body projecting from the polarizing electrodes and a negative lead part 304 consisting of a part of the collector foil of the negative electrode body projecting from the polarizing electrodes. That is, the accumulator cells 301 each have a positive lead part 303 at one end of the wound body and have a negative lead part 304 at the other end of the wound body.
By a plurality of these accumulator cells 301 being disposed on the same axis and the positive lead part 303 of one of the accumulator cells 301 being connected to the negative lead part 304 of another, the accumulator cells 301 are connected in series to form an accumulator cell unit 305. This accumulator cell unit 305 is received in a metal case 302 and a cylindrical battery 300 is thereby obtained.
However, with the cylindrical battery 300 of related art described above, to connect a plurality of the accumulator cells 301 in series, it is necessary to make the positive lead part 303 project from one end of each of the accumulator cells 301, make the negative lead part 304 project from the other end, and connect the positive lead parts 303 and the negative lead parts 304 of adjacent accumulator cells 301.
Here, if the length of the positive lead part 303 projecting from one end of each accumulator cell 301 is written La and the length of the negative lead part 304 projecting from the other end of the accumulator cell 301 is written Lb, then to connect a number of accumulator cells 301 in series it is necessary for the adjacent accumulator cells 301, 301 to be disposed with a spacing therebetween of La+Lb, the sum of the length La of the positive lead part 303 and the length Lb of the negative lead part 304.
Because adjacent accumulator cells 301, 301 are disposed with a spacing La+Lb like this, it is difficult to keep the overall length of the cylindrical battery 300 compact.
Also, because to connect multiple accumulator cells 301 in series the positive lead part 303 of one of adjacent accumulator cells 301, 301 is connected to the negative lead part 304 of the other accumulator cell 301, when a current flows, relatively large connection resistances arise at the connections, and it is difficult to make the resistance of these connections low.
Because of this, a series accumulator cell connection structure has been awaited with which it is possible to reduce the length of a cylindrical battery to make it compact and it is also possible to keep connection resistances low.